religious ritual vs ceremony

religious ritual and ceremony both are nouns.

Word	Noun	Adjective	Verb	Adverb
religious ritual	Yes	No	No	No
ceremony	Yes	No	No	No

As nouns, ceremony is a hypernym of religious ritual; that is, ceremony is a word with a broader meaning than religious ritual:

religious ritual (noun)	ceremony (noun)
a ceremony having religious meaning	the proper or conventional behavior on some solemn occasion
	any activity that is performed in an especially solemn elaborate or formal way
	a formal event performed on a special occasion